A cantilever parasol of the type mentioned at the outset is known from WO 98/08411 A1. Displacement—that is to say, extension and retraction—of an arm on an arm mounting which is arranged at the upper end of the mast presents problems, because as the length of extension of the arm on the arm mounting increases, the arm tilts and clamps, with the result that the arm can in practice only be further displaced by lifting it. These problems are reinforced by the parasol being attached to the arm by means of a ball-and-socket joint, which allows the parasol to be further adjusted and adapted. However, this increases the risk that the arm will tilt sideways during displacement. Similar problems also arise, moreover, when a telescopic mast of a cantilever parasol of this kind is adjusted in height.
Various constructions of cantilever parasols are known, allowing adjustment as the sun moves across the sky. WO 2005/018369 A1 discloses a cantilever parasol in which the arm is connected to the mast by means of a height-adjustable slide. A supporting strut connects the upper mast end to the central region of the arm. The disadvantage here is that the supporting strut determines a guidance curve, so there are limitations to the way the arm can be adjusted in the horizontal direction, independently of a guide support. This type of construction is not height-adjustable, is weighty and is bulky to ship.
Tests have shown that guiding the arm by means of rollers does not in itself solve the problem. If the rollers are arranged below and above the arm, the extension movement begins to stick as the length of extension increases. To enable complete extension to be performed smoothly, with this type of construction too it is necessary to lift the parasol part somewhat and to extend the arm forward of the parasol part or retract it again. Additional problems arise if the arm is in the form of an arc, since this construction is prone to sideways tilting and clamping. This is exacerbated by the fact that the arm is typically difficult to access from the parasol side, because of furniture that is set up in the shade of the parasol.